46 THE SOILS AKD CBOPS OF THE FXti^. 



water which flows from a heap of stable manure will 

 not only carry away some of the small fragments of 

 litter but will be discolored and offensive to smell and 

 taste because it has absorbed and holds gases and dis- 

 solved solid substances. If this water be made to 

 pass through a vessel containing finely divided soil, 

 it will come out comparatively pure as tested by sight, 

 smell and taste. The soil has not only collected on 

 its surface the matter which was not finely enough 

 divided to enter the pores of the soil, but its particles 

 have had a stronger attraction for the dissolved solids 

 than that possessed by the water. If, however, a 

 large quantity of water charged with this solid matter 

 passes through the soil, the power of the soil to absorb 

 the solid matter will be exhausted and the water will 

 come through in much the same condition in which 

 it entered the soil. If now pure water be passed 

 through this soil fully charged with the solid matter 

 it has absorbed, the water will flow out more or less 

 affected in color, smell and taste. Did not soils 

 have this power, the water in many wells would be 

 unfit for use. That it does not possess this property 

 in unlimited degree is illustiiated by the fact that the 

 water in a good many wells is unfit for use. 



Clay soils possess this power in a much greater de- 

 gree than sandy soils. A soil with much humus 

 also has this power in a noticeable degree. In a sandy 

 soil there is much more loss of plant food by the leach- 

 ing power of water than in a clayey or humus soil. 



Absorption ami Condennation of Oases. — 

 It has already been indicated that soils have the power 

 of absorbing gases from air or from water. The 

 offensive smell of decaying animal matter is entirely 



